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LI. On Fulgurites in the Andesite of the Lesser, Ararat and on 

 the Influence of Local Agents on the Production of Thunder- 

 storms. ByM. Abich*. 



THE influence of the geographical distribution of mountain- 

 masses on the limit-lines between the eastern over-heated 

 (and therefore over-dried) steppe-atmosphere of the continent of 

 Asia, and the moist and cooler masses of air brought by north- 

 west atmospherical currents, is nowhere so conspicuous as within 

 the region of the Great and Lesser Ararat group, where it finds 

 its highest expression in the beginning of the sestival half of the 

 year, under the form of frequent and sudden thunderstorms in 

 the summit-region. These phenomena stand in close relation 

 with the orographical constitution of the mountain-group. The 

 first clouds and the first electrical discharges within them begin 

 generally on the north-west side of the group, where its most 

 powerful massif reaches furthest into the region of the Araxes 

 valley, conspicuously spreading in breadth. The thunderstorm, 

 in its rapid development, soon envelopes in a south-east direction 

 the whole top region of the mountain, remaining stationary 

 within the space between the Great and the Lesser Ararat, the 

 north-west high portion, called "Kippgol]/'' standing at the 

 same time in full sunlight. After a shorter or a longer space of 

 time the thunderstorm dies away on the Lesser Ararat, or it 

 descends with gradually diminishing energy into the plain 

 towards Nachitshevan and Dzaulze. These well-characterized 

 and regular thunderstorms begin in April (old style), reach 

 their maximum in May, and have considerably diminished in 

 the course of June. Although rare in July and August, they 

 may possibly break out suddenly during this period, and be thus 

 an obstacle to ascending Ararat. The journal of a meteorolo- 

 gical station at Erivan, established by M. Abich and continued 

 during more than fourteen months, registers for April 10, for 

 May 14, and for June 6 several thunderstorms in this Ararat re- 

 gion, not mentioning those which had broken out in the inter- 

 vals of the hours (six every day) fixed for the observation of the 

 instruments. 



M. Abich, having repeatedly ascended the Lesser Ararat, has 

 been enabled to ascertain some physico-lithological facts demon- 

 strating the frequence of thunderstorms in these lofty regions, and 

 of the mutual action of atmospherical and terrestrial electricity. 

 The chief rock of the Lesser Ararat is a fine-grained amphibolic 

 andesite, rising in cliffs above the slopes covered with decom- 



* From a letter to Chevalier W. de Haidinger, dated Tiflis, June 25, 1869. 

 Communicated and translated by Count Marschall, F.C.G.S. &c. 



